flex

• No release in over 8 years; stuck on version 2.6.4 and pulling the latest git breaks a LOT of things

Prepare

• Depends on itself, help2man and texi2dvi
• Depends on bison; does not work with byacc
• Touch doc/flex.1 to prevent help2man from breaking make install-strip

Configure

• Explicitly specify ac_cv_func_malloc_0_nonnull=yes ac_cv_func_realloc_0_nonnull=yes otherwise it will be guessed as no
• Nothing uses libfl and gcc will complain regardless if libfl exists or not

References

• https://github.com/westes/flex/issues/337
• https://github.com/westes/flex/milestone/5